1. Field of the Invention
The present invention relates to an interface circuit, more particularly to an interface circuit for use in an electronic device without a synchronized dock connector and the electronic device.
2. Description of the Related Art
Referring to FIGS. 1 and 2, a conventional plug and play electronic device without a synchronized dock connector usually comprises an audio signal output circuit 920 that has an audio terminal 910 (e.g., a 3.5 mm phone jack) and that outputs an audio signal including AUDIO_R and AUDIO_L, a program updating circuit 940 that has a transceiving port connector 930, and a Microcontroller unit (MCU) 950. The program updating circuit 940 transmits an updating information to the MCU 950 for updating firmware or program stored in the MCU 950 when the updating information is received by the electronic device. Accordingly, two interface circuits (i.e. the audio signal output circuit 920 and the program updating circuit 940) are required in such an electronic device, resulting in relatively high manufacturing costs. In addition, the program updating interface circuit 940 is usually idle and is only in use when an update is performed.